2nd Workshop

International Oxy-Combustion Research Network Hilton Garden Inn Windsor, CT, USA

25th and 26th January 2007

Hosted by:

Alstom Power Inc.

PRESENTATION - 18

Packed Bed Reactor Technology for Chemical-Looping Combustion

by: Sander Noorman University of Twente, The Netherlands

2nd Int'l Oxy-Combustion Workshop Page 1

Packed Bed Reactor Technology for Chemical-Looping Combustion

S. Noorman, M. van Sint Annaland, J.A.M. Kuipers (UT)N.A.M. ten Asbroek, P.H.M. Feron (TNO)

2nd IEAGHG Oxyfuel Combustion Workshop25th and 26th of January 2007, Windsor, USA

2

Chemical-looping Combustion

• Power production with inherent CO2 separation• Direct contact between air and fuel is avoided

MeO

Me

Air

N2

CO2, H2O

Fuel

I II

I: 4 Me + 2 O2 → 4 MeO (∆H < 0)

II: 4 MeO + CH4 → 4 Me + CO2 + 2 H2O (∆H > 0)

2nd Int'l Oxy-Combustion Workshop Page 2

3

Introduction

• Chemical-looping Combustion: Potential for very high CO2capture efficiencyNo energy penalty for separationNo NOx formationDirect implementation in power plants is challenging

• Important research themes:Oxygen carrier (MeO = NiO, Fe2O3, Mn3O4, CuO)Implementation in power plantReactor concepts

MeO

Me

Air

N2

CO2, H2O

Fuel

I II

I: 4 Me + 2 O2 → 4 MeO (∆H < 0)

II: 4 MeO + CH4 → 4 Me + CO2 + 2 H2O (∆H > 0)

MeO

Me

Air

N2

CO2, H2O

Fuel

I II

I: 4 Me + 2 O2 → 4 MeO (∆H < 0)

II: 4 MeO + CH4 → 4 Me + CO2 + 2 H2O (∆H > 0)

Oxidizing and reducing conditions must be imposed alternately

4

Air CH4

N2/O2

CO2/H2O

Air CH4

N2/O2

CO2/H2O

Reactor Concepts

Recirculation or stationary solids?

• Disadvantage of fluidization:Recirculation of particlesDifficult gas-solid separation (formation of fines)

• Packed bed (membrane-assisted) CLC:

Stationary solidsPeriodic switching of gas streamsDynamically operated parallel reactors (gas switching system)Natural gas → combined cycle!

2nd Int'l Oxy-Combustion Workshop Page 3

5

Packed Bed CLC

• Process demands:Constant high-temperature air streamHigh overall and CO2 capture efficiencyContinuous operationExtreme conditions (Tout = 1300-1500 K, p = 20-30 bar)

• Packed bed CLC (UT): • Packed bed membrane-assisted CLC (TNO):

Air

CH4

N2/O2

CO2/H2O

(n ≥ 2)Air

CH4

N2/O2

CO2/H2O

(n ≥ 2)

6

Project Goal

• Evaluation of the feasibility of packed bed CLC as an alternative power production technology:

Can CLC be carried out using packed bed (membrane-assisted) technology?How can packed bed CLC with an optimal overall energy efficiency be realized?How does packed bed CLC perform, compared to fluidized bed CLC and other CO2 capture processes?

• This presentation:Modeling and experimental work on packed bed CLC.

2nd Int'l Oxy-Combustion Workshop Page 4

7

Packed Bed CLC: Oxidation

Air

N2/O2

MeMeO

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

Con

cent

ratio

n [-]

Axial position [m]O2MeO

• Oxidation cycle:Calculation of axial temperature and concentration profiles.Particle behavior is described using a two-zone model

8

0 500 1000 1500 2000 2500850

900

950

1000

1050

1100

1150

1200

Tem

pera

ture

at x

=L [K

]

Time [s]

• ‘No’ influence of reaction kinetics or flow rate• An air stream of high, constant temperature

is produced → gas turbine

Packed Bed CLC: Oxidation

Air

N2/O2

0.0 0.2 0.4 0.6 0.8 1.0850

900

950

1000

1050

1100

1150

1200

Tem

pera

ture

[K]

Axial position [m]

• Oxidation cycle:Temperature evolution

2nd Int'l Oxy-Combustion Workshop Page 5

9

Oxygen Carrier Properties

• Analytical approximation:Infinitely high reaction rateNo influence of conduction

• Temperature increase can be tuned:

Active content Support materialOxygen concentration

0.00 0.05 0.10 0.15 0.20 0.25 0.300

200

400

600

800

1000 NiO (ox)CuO (ox)

Mn3O4 (ox)

Tem

pera

ture

diff

eren

ce [K

]

wact [-]

Fe2O3 (ox)

2

2ξ

−∆∆ =

− ,,

,

( )R

p g Op s actin

act g O

HT C MC Mw w

10

Packed Bed CLC: Reduction

CH4

CO2/H2O

MeOMe

0.0 0.2 0.4 0.6 0.8 1.00.0

0.2

0.4

0.6

0.8

1.0

CH4

Con

cent

ratio

n [-]

Axial position [m]

MeO

• Reduction cycle:Efficient use of fuelHigh CO2 capture efficiencySelectivity to CO2 and H2OIncomplete regeneration of part of the bed

2nd Int'l Oxy-Combustion Workshop Page 6

11

Packed Bed CLC: Operation

• Operation over multiple cycles:

0 500 1000 1500 2000 2500

900

1000

1100

1200

1300

Tem

pera

ture

at x

=L [K

]Time [s]

0.0 0.2 0.4 0.6 0.8 1.0850

900

950

1000

1050

Tem

pera

ture

[K]

Axial position [m]

Fluidization between oxidation and reduction cycles is necessary to level off temperature profiles.

12

Modeling Packed Bed CLC

→ Cyclic steady state is obtained after only a few oxidation/reduction cycles.

0 2000 4000 6000 8000 1000012000

900

1000

1100

1200

1300

Tem

pera

ture

at x

=L [K

]

Time [s]

Reduction Oxidation

2nd Int'l Oxy-Combustion Workshop Page 7

13

Experimental Validation

14

Experimental ValidationModel description Experimental results

0.6 0.7 0.8 0.9 1.0900

950

1000

1050

1100

1150

Tem

pera

ture

[K]

Axial position [m]0.6 0.7 0.8 0.9 1.0

900

950

1000

1050

1100

1150

Tem

pera

ture

[K]

Axial position [m]

Oxidation reaction:

(Cu/CuO, wact ≈ 0.1)➼199195∆Tmax [K]

0.13

1.53

Model

➼0.15w1 [cm/s]

➼1.58w2 [cm/s]

Exp.Improvements:• Correct implementation of heat losses in the model• Coupling of particle model and reactor model

(t = 0, 6, 12, 18, 24, 30 s)

2nd Int'l Oxy-Combustion Workshop Page 8

15

Implementation

Reactor 1 Reactor 2

Rea

ctor

Exi

tTe

mpe

ratu

re [K

]

Time

• Implementation in power plant:Combined cycle to maximize overall energy efficiency

• Process design:Pressure dropNumber of reactorsReactor sizingHeat integration, etc.

• Important features:Compact designSuitable for part-load operation

16

Conclusions

• Packed bed (membrane-assisted) CLC is an interesting alternative power production technology:

• Process operation:Oxidation cycle: generation of high temperature air streamReduction cycle: combining efficient use of fuel and high CO2 capture efficiency

• Implementation in power plant:Combined cycle

• Future work:Experimental validation of packed bed CLCProcess design and efficiency calculations